docs(website): correct signing claims and refresh the roadmap

Three surfaces still described Portal as a signed download, contradicting the
ad-hoc signing decision already committed in this branch: the source comment,
quick-start step 02, and the start-note. The note now also states the real
preview-matrix position rather than claiming Linux and Windows are source-only.

Issue #7 shipped, so bounded Iroh/MoQ media objects move out of "hardening
next" and into the section intro as landed work, keeping the issue link the
website gate requires. That frees a grid slot for the 1:N pivot (#74), worded
to avoid overclaiming: today a session admits exactly one client, and the card
says so plainly alongside "not built yet".

Both grids still divide evenly, 6 across 3 columns and 4 across 2, so neither
gains a ragged row showing the hairline background.

Also surfaces the Decky Loader plugin, which is real, packaged, and CI-gated
but was never mentioned on the site.

Adaptive bitrate and motion-sensitive resolution are deliberately NOT presented
as partially delivered. They only actuate on the opt-in in-process encoder
backend, so their cards continue to read as upcoming work.

commit

3b65bac7bf31691e5d09ac942a0ba40bea14c028

parent

9588dac08f7119613ef236a051b798c70cfc35c9

author

Dami <dami.etoile@gmail.com>